Film carrier tape for semiconductor package and manufacturing method thereof

ABSTRACT

A film carrier tape and a method of forming a film carrier tape that incorporates a polymeric reinforcement film are provided for decreasing the deformation of and damage to film carrier tapes by forces resulting from contact with sprocket teeth during the semiconductor assembly process. The reinforcement film may include one or more synthetic resins and may increase the useable area of a base film used in forming film carrier tapes.

[0001] This U.S. nonprovisional patent application claims priority under35 U.S.C. § 119 from Korean Patent Application 2002-43541, filed Jul.24, 2002, Korean Patent Application 2003-28980, filed May 7, 2003, andKorean Patent Application 2003-31400 filed May 17, 2003, the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a film carrier tape for asemiconductor package and a manufacturing method thereof and, moreparticularly, a film carrier tape having a reinforcing film forincreasing the strength of the film carrier tape.

[0004] 2. Description of the Prior Art

[0005] As electronic devices become miniaturized and multi-functional,the semiconductor packages used in the electronic devices also need tobe smaller. Several types of packages have been developed in response tothis demand including tape carrier packages (TCP) and chip-on-filmpackages (COF). Both tape carrier packages and chip-on-film packages aremanufactured using a thin film rather than a lead frame or a printedcircuit board (PCB) for mounting the semiconductor chips. For massproduction of TCP or COF, a film carrier tape on which a plurality ofpackages may be formed is typically used.

[0006] The structure of a conventional film carrier tape will bedescribed with reference to FIGS. 1-3. FIG. 1 is a perspective view of aconventional film carrier tape (10) comprising a base film (100), awiring pattern (154) formed on the upper side of the base film (100) anda reinforcement metal pattern (152). The base film (100) comprises amain area (110) on which the wiring pattern is formed, and a peripheralarea (120) on which a plurality of sprocket holes (122) is formed.

[0007] The sprocket holes (122) are used for transporting the filmcarrier tape by a rotating sprocket. The reinforcement metal pattern(152) is formed on the peripheral area (120) of the base film (100) toreduce the likelihood that the sprocket holes (122) will be torn by thesprocket teeth (not shown), and to enhance the strength of the base film(100). The base film (100) is usually made of one or more layers ofsynthetic resin such as polyimide, and may have a thickness of about 38μm.

[0008] The wiring pattern (154) and the reinforcement metal pattern(152) are usually made of conductive metals such as copper (Cu), and mayhave a thickness of about 8 μm. The wiring pattern (154) and thereinforcement metal pattern (152) can be made by patterning and etchinga thin metal layer formed on the base film (100).

[0009] In a typical manufacturing process, a film carrier tape havingtwo or more lanes of films may be used to enhance the efficiency of themanufacturing process. FIG. 2 is a perspective view showing a filmcarrier tape having two lanes of film that can be used in a conventionalmanufacturing process.

[0010] As shown in FIG. 2, each of the lane's film (15) has a width (A),typically 35 mm, and are formed on a film carrier tape (30) having awidth (B), typically 105 mm, for use in the conventional manufacturingprocess.

[0011] The metal layer (150) which will be patterned and etched to formthe wiring pattern and the reinforcement metal pattern is formed on theupper surface of a base film (105). A supplementary film (130) may beattached to the lower surface of the base film (105).

[0012] In order to form the uniform reinforcement metal pattern and thewiring pattern, a liquid photoresist needs to be applied evenly acrossthe metal layer (150) on the base film (105). However, the liquidphotoresist applied on the outermost peripheral areas of the filmcarrier tape (30) runs down through the outermost sprocket holes (160)which were formed before the patterning and etching process to providefor the transfer of the film carrier package. Therefore, the area ofbase film (105) near the sprocket holes (160) cannot be used and arewasted. The sprocket holes (132) of each lane of the films (15) areformed after the photoresist becomes hardened. Therefore, although threelanes of film could be formed on the film carrier tape given the typicalwidths of each lane of the film (15) and the film carrier tape (30),only two lanes of film can be formed on the film carrier tape in theconventional manufacturing process.

[0013] The supplementary film (130) usually includes one or moresynthetic resins such as polyethylene terephthalate (PET), and may havea thickness of about 50 μm. After manufacturing the film carrier tape(30), the supplementary film (130) may be removed from the lower surfaceof the base film (105).

[0014] A solder resist layer is usually formed on the metal layer (150)of the film carrier tape (30), to a thickness of about 12 μm in order toreduce oxidization of the metal layer (150).

[0015]FIG. 3 shows the result of a computer simulation of thedeformation of the conventional film carrier tape under pressure. Asshown in FIG. 3, the deformation of the film carrier tape is greatestnear the surface on which the sprocket directly exerts force despite thereinforcement metal pattern provided on the peripheral area of the film.

[0016] In addition, the sprocket holes may be easily torn by thesprocket, because the reinforcement of the reinforcement effect of theconventional reinforcement metal pattern is not sufficient.

[0017] In addition, a large amount of films are wasted for forming thereinforcement metal pattern by the above-describe reason..

SUMMARY OF THE INVENTION

[0018] Exemplary embodiments of the invention provide a film carriertape having an improved reinforcement structure and a method formanufacturing such a film carrier tape.

[0019] An exemplary film carrier tape according to the inventioncomprises a base film and a reinforcement film. The base film has a mainarea where a wiring pattern is formed and a peripheral area where aplurality of sprocket holes are formed. The reinforcement filmreinforces the base film attached to the peripheral area of the basefilm and is formed from a material that is different than the materialused to form the wiring pattern. The wiring pattern of an exemplaryembodiment may be formed on an upper surface of the base film, and thereinforcement film may be attached to a lower surface of the base film.The reinforcement film may be made from one or more synthetic resins andmay include a resin selected from a group consisting of polyethyleneterephthalate, liquid crystalline polymer, polytetrafluoroethylene,polypropylene, polyethylene, polyamide-66, and polycarbonate. Thereinforcement film may have a thickness of 20-80 μm and may includesprocket holes formed through the reinforcement film.

[0020] An exemplary method of manufacturing such a film carrier tapecomprises (a) attaching a raw film to a base film having a main area anda peripheral area, (b) forming a plurality of sprocket holes on theperipheral area of the base film, (c) forming a wiring pattern on themain area of the base film, (d) cutting the raw film along a boundarybetween the main area and the peripheral area of the base film, and (e)forming a reinforcement film by removing the portion of the raw filmcorresponding to the main area of the base film. In another exemplaryembodiment, the raw film may be cut (step (d)) before the wiring patternis formed on the base film (step (c)). Similarly, the raw film may beattached to the lower surface of the base film, and the wiring patternmay be formed the upper surface of the base film.

[0021] The raw film may be made from one or more synthetic resins andmay include a resin selected from a group consisting of polyethyleneterephthalate, liquid crystalline polymer, polytetrafluoroethylene,polypropylene, polyethylene, polyamide-66, and polycarbonate. The rawfilm may have a thickness of 20-80 μm or may be manufactured to provideraw films of other ranges of thickness depending on the application andthe materials selected.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above features and advantages of the present invention willbecome more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings in which:

[0023]FIG. 1 shows a conventional film carrier tape with a reinforcementmetal pattern;

[0024]FIG. 2 shows a conventional film carrier tape on which two lanesof films are formed;

[0025]FIG. 3 shows the graphic results of a computer simulation of thedeformation of a conventional film carrier tape with a reinforcementmetal pattern;

[0026]FIG. 4 shows a film carrier tape with a reinforcement filmaccording to an exemplary embodiment of the invention;

[0027]FIG. 5 is a block diagram showing the manufacturing process of anexemplary reinforcement film;

[0028]FIG. 6 shows an exemplary process in which a raw film is attachedto a base film;

[0029]FIG. 7 shows an exemplary process in which a plurality of sprocketholes are formed on the base film and the raw film;

[0030]FIG. 8 shows an exemplary process in which a wiring pattern isformed on the base film;

[0031]FIG. 9 shows an exemplary process in which a portion of the rawfilm attached to the main area is removed from the base film; and

[0032]FIG. 10 shows the results of a computer simulation of thedeformation of the improved film carrier tape with a reinforcement filmaccording to an exemplary embodiment of the invention.

[0033] FIGS. 11(a) and 11(b) show the deformation of the sprocket holecaused by the sprocket.

DETAILED DESCRIPTION OF EXAMPLARY EMBODIMENT

[0034] An exemplary film carrier tape and an exemplary method formanufacturing such a film tape carrier according to the presentinvention will be described referring to FIGS. 4-10. FIG. 4 shows a filmcarrier tape with a reinforcement film attached to the lower surface ofthe base film. As shown in FIG. 4, the film carrier tape comprises abase film (200), a wiring pattern (254) and a reinforcement film (243).As with the conventional film carrier tape, the base film (200)comprises a main area (210) on which the wiring pattern is formed and aperipheral area (220) where a plurality of sprocket holes (222) areformed. The reinforcement film (243) is attached to the lower surface ofthe peripheral area (220) and has a plurality of sprocket holes (232)corresponding to and aligned with the sprocket holes (222) of the basefilm (200).

[0035] The base film (200) may be made from one or more synthetic resinssuch as liquid crystalline polymer (LCP), polyetheretherketone (PEEK),or preferably polyimide (PI). The base film (200) may have a thicknessof 25-50 μm and may have a typical thickness of about 38 μm.

[0036] The wiring pattern (254) is made of conductive metal such asaluminum (Al), silver (Ag), copper (Cu), or an alloy of one or more ofthese metals. The wiring pattern (254) may have a typical thickness of6-8 μm and may be formed by patterning and etching a metal layer formedon the main area (210) of the base film (200). A chip installation hole(212), where a chip will be installed, may be formed on the main area(210) of the base film (200).

[0037] The reinforcement film (243) may be made of a synthetic resinsuch as liquid crystalline polymer (LCP), polytetrafluoroethylene(PTFE), polypropylene (PP), polyethylene (PE), polyamide 66 (PA-66),polycarbonate (PC), or more preferably polyethylene terephthalate (PET).The reinforcement film (243) usually may have a thickness of 20-80 μmand more typically about 50 μm.

[0038] TABLE 1 shows the characteristics of selected synthetic resinsthat may be used for the reinforcement film (243). TABLE 1 PI LCP PTFEPP PE PET PA-66 PC Heat V V G N N N N N Resistance Cost P G G V V V V V

[0039] As seen from TABLE 1, several kinds of synthetic resins can beused for the reinforcement film (243). PET, for example, provides anacceptable combination of cost and material characteristics for areinforcement film.

[0040] The reinforcement film (243) may be attached to the base film(200) using an acryl or epoxy type adhesive layer of 5-15 μm. Thesprocket holes (222) of the base film (200) and the sprocket holes (232)of the reinforcement film (243) will typically be aligned with eachother. A solder resist layer of 5-20 μm may be formed on the wiringpattern (254) for reducing the oxidization of the wiring pattern (254).

[0041] The invention may be adapted to film carrier tape having morethan two lanes of film, in order to enhance the efficiency of themanufacturing process.

[0042]FIG. 5 is a flow chart illustrating an exemplary manufacturingprocess for producing an exemplary film carrier tape according to theinvention. FIGS. 6-9 illustrate the construction of a film carrier tapeaccording to the manufacturing steps (40-44) identified in FIG. 5. Eachmanufacturing step of the film carrier tape will be described withreference to FIGS. 5-9.

[0043] As shown in FIG. 6, the metal layer (250) is formed on the uppersurface of the base film (205). A raw film (240) supports the base film(205) is attached to the lower surface of the base film (205) asreflected in step (40) of FIG. 5. In this embodiment, three lanes offilm (25) of width (A′) are formed on the film carrier tape (50) whosewidth (B′) is three times (A′). The width of the raw film (245) istypically the same as that of the film carrier tape (50).

[0044] After the raw film is attached to the base film (205), sprocketholes (223) are formed through the base film and the raw film (240) byperforating the base film and the raw film simultaneously as shown inFIG. 7 and reflected in step (41) of FIG. 5. The sprocket holes (223)are formed on the outmost area of the film carrier tape (50) and areused for transferring the film carrier tape using a sprocket.

[0045] After the sprocket holes (223) are formed, the wiring pattern(255) is formed on the base film (205) as shown in FIG. 8 and reflectedin step (42) of FIG. 5. In the step (42), a chip installation hole (214)where a semiconductor chip can be positioned may also be formed. Thewiring pattern (255) may be manufactured by patterning and etching themetal layer (250) provided on the base film (205).

[0046] After the wiring pattern (255) is formed on the base film (205),the raw film (240) is cut along the boundary between the main area (215)and the peripheral area (225) of the base film (205) as reflected instep (43) of FIG. 5. The step (43) may also be performed before step(42).

[0047] After the raw film (240) is cut, the portion (246) of the rawfilm (240) attached to the main area (215) of the base film (205) isremoved from the base film (205) as shown in FIG. 9 and as reflected instep (44) of FIG. 5. The remaining portion of the raw film (240)attached to the peripheral area (225) remains to form the reinforcementfilm (245).

[0048] According to the described embodiment of the present invention,the reinforcement film (245) is used instead of a conventionalreinforcement metal pattern to strengthen the film carrier tape (50).Therefore, the liquid photoresist may be applied only on the main area(215) of the base film (205) during the manufacturing process. Byremoving the need to apply the liquid photo resist on the peripheralareas (225) of the base film (205), the problems associated withphotoresist running down through the sprocket holes (223) are reduced oreliminated, and the outermost sprocket holes can be used as the sprocketholes of an outer lane of film. As a result, the utilization of the basefilm (205) may be improved when compared with the conventionaltechnology by using the reinforcement film (245) disclosed in theexemplary embodiment of the present invention.

[0049] After all steps for manufacturing the reinforcement film (245)are finished, the film carrier tape (50) may be divided into threeindividual reinforced film carrier tapes with each divided film carriertape available for a semiconductor package manufacturing process.

[0050]FIG. 10 shows the result of a computer simulation of thedeformation of the improved film carrier tape of the present inventionunder pressure.

[0051] Compared with the simulation result of the conventionaltechnology using the traditional reinforcement metal pattern shown inFIG. 3, the deformation of the film carrier tape caused by an identicalforce applied by a sprocket is reduced. The reinforcing effect of thepresent invention is improved compared to that of the conventionaltechnology and will reduce the likelihood of damage caused by thesprocket during a manufacturing operation.

[0052] FIGS. 11(a) and 11(b) show the deformation of sprocket holescaused by the sprocket. FIG. 11(a) shows the shapes of sprocket holebefore and after the deformation. In order to describe the deformationpattern of the sprocket holes, the deformation was measured at 8equi-spaced positions along the X-direction in FIG. 11(a). FIG. 11(b)shows the deformation of the sprocket holes at the above-described 8equi-spaced positions. As shown in FIG. 11(b), the deformation of thesprocket hole according to the present invention is much smaller thanthat according to the conventional art using the reinforcement metalpattern made of Cu.

[0053] Although a certain preferred embodiment of the present inventionhas been shown and described in detail, it should be understood thatvarious changes and modifications may be made therein without departingfrom the scope of the appended claims.

What is claimed is:
 1. A film carrier tape comprising: a base film, thebase film formed of a first material and including a main area on whicha wiring pattern is formed and a peripheral area; and a reinforcementfilm formed of an insulating second material, the reinforcement filmbeing provided on the peripheral area of the base film; wherein aplurality of sprocket holes formed through the reinforcement film andthe peripheral area of the base film.
 2. A film carrier tape accordingto claim 1, wherein: the base film has a upper surface and a lowersurface, and further wherein the wiring pattern is formed in the mainarea on the upper surface of the base film, and the reinforcement filmis attached to the lower surface of the base film.
 3. A film carriertape according to claim 1, wherein: the reinforcement film is formedfrom a synthetic resin.
 4. A film carrier tape according to claim 1,wherein: the synthetic resin includes at least one substance selectedfrom a group consisting of polyethylene terephthalate, liquidcrystalline polymer, polytetrafluoroethylene, polypropylene,polyethylene, polyamide-66 and polycarbonate.
 5. A film carrier tapeaccording to claim 4, wherein: the synthetic resin includes a majorportion of polyethylene terephthalate.
 6. A film carrier tape accordingto claim 1, wherein: the reinforcement film has a thickness of 20-80 μm.7. A film carrier tape according to claim 6, wherein: the base film hasa thickness of 25-50 μm.
 8. A method of manufacturing a film carriertape comprising: attaching a raw film to a base film, the base filmincluding a main area and a peripheral area; forming a plurality ofsprocket holes through the peripheral area of the base film and the rawfilm; forming a wiring pattern on the main area of the base film;cutting the raw film along a boundary between the main area and theperipheral area of the base film; and removing a central portion of theraw film corresponding to the main area of the base film, whereby aremaining portion of the raw film reinforces the peripheral area of thebase film.
 9. A method of manufacturing a film carrier tape according toclaim 8, wherein: the raw film is attached to a lower surface of thebase film and the wiring pattern is formed on an upper surface of thebase film.
 10. A method of manufacturing a film carrier tape accordingto claim 8, wherein: wherein the raw film includes a synthetic resin.11. A method of manufacturing a film carrier tape according to claim 8;wherein: the synthetic resin includes at least one substance selectedfrom a group consisting of polyethylene terephthalate, liquidcrystalline polymer, polytetrafluoroethylene, polypropylene,polyethylene, polyamide-66 and polycarbonate.
 12. A method ofmanufacturing a film carrier tape according to claim 8, wherein: thesynthetic resin includes a major portion of polyethylene terephthalate.13. A method of manufacturing a film carrier tape according to claim 8,wherein: the wiring pattern is formed on the main area of the base filmbefore the raw film is cut along the boundary between the main area andthe peripheral area of the base film.
 14. A method of manufacturing afilm carrier tape according to claim 8, wherein: the wiring pattern isformed on the main area of the base film after the raw film is cut alongthe boundary between the main area and the peripheral area of the basefilm.
 15. A method of manufacturing film carrier tapes comprising:attaching a raw film to a base film, the base film having a plurality ofmain areas and a plurality of peripheral areas bounding the main areas;forming a plurality of sprocket holes through the peripheral areas ofthe base film and the raw film; forming a plurality of cuts through theraw film along a plurality of boundaries between the main areas and theperipheral areas of the base film; forming a plurality of wiringpatterns on the main areas of the base film; removing portions of theraw film from the main areas of the base film, whereby remainingportions of the raw film reinforce the peripheral areas of the basefilm; and separating the base film along the peripheral areas to form aplurality of film carrier tapes.
 16. A method of manufacturing filmcarrier tapes according to claim 15, wherein: attaching the raw film tothe base film includes forming an adhesive layer between a surface ofthe raw film and an opposing surface of the base film.
 17. A method ofmanufacturing a film carrier tape according to claim 15, comprising:attaching a raw film to the base film; forming a plurality of sprocketholes through the peripheral area of the base film and the raw film;forming the wiring pattern on the main area of the base film; cuttingthe raw film along a boundary between the main area and the peripheralarea of the base film; and removing a central portion of the raw filmcorresponding to the main area of the base film, whereby a remainingportion of the raw film form the reinforcement film.